In the past, an inspection apparatus for detecting defects at a circumferential end face of a semiconductor wafer (external inspection apparatus) has been proposed (for example, Patent Literature 1). This inspection apparatus scans the circumferential end face of the semiconductor wafer under inspection by a line sensor and analyzes the image obtained based on the density (gray-scale) signal obtained for each pixel at that time to generate information showing defects, scratches, foreign matter, etc. at the circumferential end face. According to such an inspection apparatus, it is possible to judge a relief state of the circumferential end face of a semiconductor wafer or what kind of defects there are at the circumferential end face.
In this regard, the process of production of a semiconductor wafer includes a step of forming an oxide film, nitride film, polycrystalline silicon film, aluminum film, and other films, a photolithography step of coating, exposing, and developing a photosensitive material (resist) etc., a step of etching to partially remove the resist film formed on the semiconductor wafer in the photolithography step, etc. If it were possible to learn the states of the various types of films formed on the surface of a semiconductor wafer by such steps, it would be possible to judge if the conditions in the film-forming step, photolithography step, and etching step were suitable. For this reason, it has been desired to detect the states of films on the semiconductor wafer surface as well as the scratches and other defects.
Patent Literature 1: Japanese Patent Publication (A) No. 2000-114329